There is abundant evidence to indicate that DDT is a safe material under actual conditions of use. Although it occurs in our diet, and is stored in our fat, there is no indication that the amounts involved are injurious. Human beings, as well as animals, can withstand much greater exposure and much greater storage than are now prevalent. The greatest recent advances in our knowledge of DDT are those which define the current exposure and the magnitude of tolerable dosages involving this compound which has contributed so significantly to public health and to agriculture. This quantitative information based on human rather than animal exposure should do much to satisfy any reasonable doubts about the safety of DDT.